The present invention relates generally to fabric fasteners of the type commonly referred to as hook-and-loop fasteners. More particularly, the present invention relates to a novel warp-knitted loop-type textile fastener fabric having pile loops that extend diagonally relative to the fabric extent and a method of producing such a fastener fabric on a warp knitting machine.
So-called hook-and-loop fasteners have gained considerable popularity over recent years. Such fasteners basically include two generally flat components attachable and detachable to and from face abutting relation with one another. Typically, the loop or xe2x80x9cfemalexe2x80x9d fastener component is of a textile fabric construction, generally having a fabric ground layer with a plurality of relatively flexible pile-type loops extending outwardly from one face of the ground layer. The hook or xe2x80x9cmalexe2x80x9d component may be of an extruded or molded plastic construction having any of various forms of relatively stiff, molded or extruded hook-shaped elements extending in upstanding relation from one face of a ground layer, or may also be of a textile fabric construction similarly having a fabric ground layer with a plurality of hook-shaped elements upstanding from one face of the ground layer. In use, the hook and loop faces of the fastener components grippingly engage one another when pressed together in face abutting relation by penetration of the hook-shaped elements of the hook component into the loops at the opposing face of the loop component. The engagement between the hook and loop faces of the two components resists separation thereof until a threshold force is exerted on one component in a peeling-like fashion.
Over recent years, it has been suggested and has become commonplace to produce the loop component fabric in a warp-knitted construction which can be made in various widths and can be engineered to be susceptible of many diverse end-use applications. The typical knitting methodology by which such fabrics are made involves knitting a ground fabric structure utilizing only selected needles of the needle bar of the warp knitting machine, e.g., usually alternate needles, while simultaneously knitting pile or other loop-forming yarns integrally with the ground fabric structure in alternate courses and holding the pile yarns on inactive needles, e.g., the intervening needles, in knitting the intervening courses. The extent of the pile yarns held on the inactive needles is cast off such needles in the knitting of the succeeding course and thereby is not knitted into the ground structure but rather extends outwardly therefrom as an extended underlap at the technical back of the fabric to form pile loops thereat. While many differing specific stitch constructions are possible within this general fabric forming criterion, all of the known loop-type fabrics of this warp knitted construction provide for knitting of each pile yarn in a single common wale, whereby the pile loops align warpwise within their respective wales. Such walewise alignment of the pile loops, however, has been found in actual use to provide a less than optimal ability of the loops to engage with hook-shaped elements of a mating hook component. Therefore, it would be desirable to improve the xe2x80x9cpeel strengthxe2x80x9d of such fabrics, i.e., the threshold force required to separate the loop and hook components from engagement with one another.
In view of the above described disadvantages of known warp knitted loop component fabrics for use in a hook-and-loop fastener, the present invention contemplates the warp knitting of such a fabric in a novel knitted structure which provides diagonally oriented pile loops, most preferably extending in alternatingly opposite diagonal directions, to optimize the availability of the loops for engagement with a mating hook component fabric and to contribute to the structural integrity of the overall fabric. An additional object of the present invention is to provide a novel warp knitting method for fabricating the loop fastener component of the present invention.
Briefly summarized, the present invention provides a warp knitted textile fabric having underlap loops at one face adapted for mated engagement with hooking elements of a hook component in a the hook-and-loop type fastener. Specifically, the fabric of the present invention comprises yarns formed in needle loops arranged in longitudinally extending wales and transversely extending courses including at least one set of ground yarns and a set of pile yarns warp knitted in respective cooperating stitch patterns wherein the pile yarns and ground yarns are interknitted in needle loops in spaced wales and spaced courses with underlap loops of the pile yarns formed at the technical back of the fabric extending diagonally between the spaced wales and spaced courses.
Preferably, at least two sets of ground yarns are utilized in the fabric, with a first set of ground yarns being formed in needle loops in spaced wales of every course and a second set of ground yarns formed in needle loops in a chain stitch pattern in the spaced wales. In a preferred embodiment, the first set of ground yarns are warp knitted in a 1-0, 4-5 stitch pattern, the second set of ground yarns are warp knitted in a 0-1, 1-0 chain stitch pattern, and the pile yarns are warp knitted in a 1-2, 0-1, 4-3, 5-4 stitch pattern. Thus, the underlap loops of the pile yarns extend outwardly from the technical back of the fabric in opposite directions coursewise of the fabric.
The present invention also contemplates a method of producing a warp knitted textile fabric suitable for use as the loop component of a hook-and-loop type fastener. Basically, the present method includes the steps of simultaneously warp knitting at least one set of ground yarns and a set of pile yarns in cooperating stitch patterns of needle loops on the needle bar to form a warp knitted fabric. More specifically, the present invention provides for the warp knitting of each pile yarn by sequentially interknitting a first needle loop of the pile yarn with a needle loop of a ground yarn on a selected needle of the needle bar, interveningly holding an extent of the pile yarn in a non-knitting manner on a second needle of the needle bar unoccupied by any ground yarn, and subsequently interknitting a second needle loop of the pile yarn with another needle loop of a ground yarn on a third needle of the needle bar while releasing the held extent of the pile yarn from the second needle without stitch formation to form an underlap loop of the pile yarn extending outwardly from the technical back of the fabric between the first and second needle loops of the pile yarn.
In the preferred embodiment of the present method, a first set of ground yarns are warp knitted in a 1-0, 4-5 stitch pattern, a second set of ground yarns are warp knitted in a 0-1, 1-0 chain stitch pattern, and the pile loop-forming yarns are warp knitted in a 1-2, 0-1, 4-3, 5-4 stitch pattern.